I always take water - either in a bottle with a sports cap, or the bottle I use when walking, which has a hose with a valve on the end, so you can drink totally hands free. If it's a hot day, I take a 50:50 mix of fruit juice and water.
As for food, picnicky things are ideal. Cold sausages or other meats, boiled eggs, bite-size pieces of fruit etc etc.
And why does ATC always want to talk to me
Conversely, why do pilots always call me up when I've just taken a huge bite of sandwich?
